1. Field of the Invention
The present invention relates to a rear transmissive projection television that uses a high output light source, particularly, a semiconductor laser as a light source and a fixing method of a screen unit thereof.
2. Description of the Related Art
In a rear transmissive projection television, an optical engine that projects an image by a light source such as a high-pressure mercury lamp and an LED lamp is included and an enlarged image is projected on a screen provided on the front side of its body. A light beam is shielded to prevent the light beam from leaking to the outside until the image projected from the optical engine is focused on the screen (see Japanese Patent Application Laid-open No. 2001-154274).
In a projection television that utilizes a mercury lamp or an LED as a light source, a screen unit in which a screen on a front side and a frame body are unified is fixed to the body with screws or the like. This screen unit is removed from the body at the time of replacement of the screen or when cleaning inside of the body (see Japanese Patent Application Laid-open No. 2002-244209).
Moreover, as a projection television equipped with a semiconductor laser as a light source, there is proposed a product that is configured such that a projection is provided on a rear cover and opening of the rear cover is detected by contact and non-contact of this projection and emission of the semiconductor laser as the light source is hampered (see Japanese Patent Application Laid-open No. 2004-148724).
However, according to the above conventional technologies, in the rear transmissive projection television that uses a semiconductor laser for red, blue, and green as a light source, when the light source is erroneously emitted in a state where the screen unit is removed for replacing a damaged screen or cleaning the inside, an intense laser beam from the optical engine may directly enter an eye of an operator, so that improvement has been required.
Moreover, in the case of providing a safety switch for avoiding emission of a laser beam of the optical engine when removing the screen unit between the screen unit and the body, many safety switches for detecting opening of a gap between the screen unit and the body need to be provided.
The present invention is achieved in view of the above and has an object of providing a projection television capable of securely preventing an intense laser beam emitted from an optical engine from accidentally entering an eye of an operator with a simple configuration and further capable of improving a design, and a fixing method of a screen unit of the projection television.